When inserting or removing a fastener with a hand tool into or from a work surface, a workman's efficiency is limited by the ability of the tool to translate mechanical force exerted by his hand to the fastener through rotary movement. For example, a tool such as a conventional screw-driver having a fixed handle mounted to a straight shaft imposes a physical limitation on the workman, allowing him to utilize only the torque which he can exert through his hand by the twisting of his wrist. Additionally, because the wrist cannot rotate completely about a circle, to complete a cycle of rotation with a conventional hand tool, the workman must periodically release his grip on the handle of the tool, rotate his hand back to a starting position and re-grip the tool handle to continue applying force.
Attempts have been made to provide rotary tools permitting better translation of the workman's exertions. For example, U.S. Pat. No. 5,349,886 to Jin discloses a hand screwdriver including a freely rotatable handle and a bent shaft having an end recess which selectively bears against one of two conical protrusions within the handle. The conical protrusions provide a fixed position wherein the shaft is fixed to the handle and a rotatable position wherein the shaft is relatively rotated with respect to the handle. The screwdriver further includes a protective coating about the upper portion of the shaft adjacent to the handle for protecting a workman from electrical shock. A shortcoming of Jin is that no means is provided for preventing rotation of the handle relative to the shaft. As such, a workman cannot impart sufficient torque to a fastener when using the screwdriver of Jin to break the fastener loose from a work surface when tightly held therein. Likewise, a workman cannot provide sufficient torque to a fastener to tightly insert it into the work surface. A further shortcoming of Jin is that the protective coating about the shaft fails to envelop the entire shaft thereby needlessly exposing a workman to electrical shock from the unprotected portions of the shaft.
U.S. Pat. No. 1,642,569 to Winslow et al discloses a hand tool including a bent shaft having a handle rotatably attached to an end thereof. Contrary to Jin, a pressure plate is slidably mounted within the handle which slips through a slot therein and is bearable against the handle, selectively fixing the handle to the shaft. This way, a workman can impart increased torque to a fastener than if the handle and shaft were not fixable together. The screwdriver of Winslow et al however provides no suitable means of disengaging the pressure plate from the shaft. For example, a workman attempting to grip the pressure plate while wearing gloves to pull the plate out of the slot will have great difficulty doing so.
Despite the above teachings of the prior art, a need still existed for a hand-powered tool which facilitates the translation of rotary motion from a workman's hand to a fastener through a freely rotating angled shaft while providing practical means of preventing rotation of the shaft when needed. Based thereon, I developed a novel combination of hand-tool accessories with the multi-functional screwdriver as disclosed and claimed in my U.S. Pat. No. 6,668,687 B1 for Multi-Functional Screwdriver. The invention in my patent provides significant advantages over the prior art. However, while an improvement, further improvement has been made to my invention and an improved multi-functional screwdriver is disclosed herein providing further advantages to the workman.